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On Wednesday, March 21 from 9:00 a.m. to 11:00 a.m. (USA Mountain Time), the following data collections will not be available due to planned system maintenance: AMSR-E, Aquarius, High Mountain Asia, IceBridge, ICESat/GLAS, MEaSUREs, MODIS, NISE, SMAP, VIIRS

EASE-Grid Land-Ocean-Coastline-Ice Masks Derived from Boston University MODIS/Terra Land Cover Data, Version 1

These Land-Ocean-Coastline-Ice (LOCI) files provide land classification masks derived from the Boston University MOD12Q1 V004 MODIS/Terra 1 km Land Cover Product (Friedl et al. 2002). The masks are available in various EASE-Grid azimuthal and global projections, at 12.5 km and 25 km spatial resolutions. The masks are in flat binary, 1 byte files stored by row. Quick-look browse images of the masks are also available in PNG (.png) format.

Detailed Data Description

Format

Masks are provided as flat binary, 1 byte files stored by row. Quick-look browse images are also available in PNG (.png) format. The masks indicate the location of land, water, coastline, and ice using coded integers. Refer to Table 1 for the key to these values:

Table 1. Key to Values Stored in LOCI Masks

Value

Description

0

Land

101

Ice

252

Coastline

254

Off the map

255

Water

Note: The software used to generate the LOCI masks sets the width of coastline pixels to a user-specified value. For this data set, the coastline width has been set to zero, i.e. the masks do not contain the value for coastline (252). Masks with non-zero coastline pixel widths are available upon request by contacting NSIDC User Services.

Each resolution and projection combination is described by a Grid Parameter Definition (GPD). The short name, grid dimensions, and file sizes for each GPD are provided in Table 2 for EASE-Grid and in Table 3 for EASE-Grid 2.0. See Table 4 for the file naming convention.

Table 2. EASE-Grid Land Classification Resolutions and Grid Sizes

Projection

Available Resolutions

Grid Dimensions (r x c)

File Size

GPD Short Name

N., S. Hemisphere

25 km

721 x 721

508 KB

Nl, Sl

12.5 km

1441 x 1441

2 MB

Nh, Sh

Global

25 km

1383 x 586

792 KB

Ml

12.5 km

2766 x 1171

3.1 MB

Mh

Table 3. EASE-Grid 2.0 Land Classification Resolutions and Grid Sizes

Projection

Parent Grid

Available Resolutions

Grid Dimensions (r x c)

File Size

GPD Short Name

N., S. Hemisphere

100 km

100 km

180 x 180

32 KB

EASE2_N100km, EASE2_S100km

10 km

1800 x 1800

3.1 MB

EASE2_N10km, EASE2_S10km

5 km

3600 x 3600

13 MB

EASE2_N05km, EASE2_S05km

36 km

36 km

500 x 500

245 KB

EASE2_N36km, EASE2_S36km

9 km

2000 x 2000

3.9 MB

EASE2_N09km, EASE2_S09km

3 km

6000 x 6000

35 MB

EASE2_N03km, EASE2_S03km

25 km

25 km

720 x 720

507 KB

EASE2_N25km, EASE2_S25km

12.5 km

1440 x 1440

2 MB

EASE2_N12.5km, EASE2_S12.5km

6.25 km

2880 x 2880

8 MB

EASE2_N6.25km, EASE2_S6.25km

3.125 km

5760 x 5760

33 MB

EASE2_N3.125km, EASE2_S3.125km

Global

36 km

36 km

964 x 406

383 KB

EASE2_M36km

9 km

3856 x 1624

6 MB

EASE2_M09km

3 km

11568 x 4872

54 MB

EASE2_M03km

25 km

25 km

1383 x 584

792 KB

EASE2_M25km

12.5 km

2776 x 1168

3.1 MB

EASE2_M12.5km

6.25 km

5552 x 2336

13 MB

EASE2_M6.25km

Temperate¹

25 km

25 km

1388 x 540

750 KB

EASE2_T25km

12.5 km

2776 x 1080

3.0 MB

EASE2_T12.5km

6.25 km

5552 x 2160

12 MB

EASE2_T6.25km

3.125 km

11104 x 4320

50 MB

EASE2_T3.125km

¹The temperate grid is a subset of the global grid that omits the most poleward latitudes. It extends from 67 N° to 67 S°.

Identifies the land threshold used in the processing of these files (50: 50% cut off used).

coastZkm

Identifies the width of the coast used in the processing of these files. Coastlines = 0 px for this data set, i.e. value for coastline not present in data.

colxrow

Grid dimensions in pixels, column x row.

.ext

File extension. .bin = binary data file, .png = PNG browse image.

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Spatial Coverage and Resolution

EASE-Grid

These data cover the entire globe and are provided in projections for the entire globe and for the Northern and Southern Hemispheres. See Table 2 for a complete listing of the projection/resolution combinations.

EASE-Grid 2.0

These data cover the entire globe and are provided in projections for the entire globe and for the Northern and Southern Hemispheres. See Table 3 for a complete listing of the projection/resolution combinations.

These EASE-Grid and EASE-Grid 2.0 land cover data sets were derived from the Boston University MODIS/Terra 1 km Land Cover Product (MCD12Q1, V004). MCD12Q1 utilizes the 17 International Geosphere Biosphere Programme (IGBP) land cover classes in Table 5.

LOCI masks were generated using the follow algorithm:

For each grid cell, calculate the percent land by summing the percent of IGBP non-water classes (1-16).

Cells with >= 50% ice are classified as ice.

Cells with >= 50% land and < 50% ice are classified as land

Any remaining cells are classified as ocean (including lakes and inland water).

Note: The LOCI masks available as part of this data set have their coastline widths set to zero pixels. As such the files do not include the value for coastline. To obtain masks with custom coastline widths, please contact NSIDC User Services.

Table 5. IGBP Land Cover Classes

Class Number

Category

Class Number

Category

01

Evergreen needleleaf forest

10

Grasslands

02

Evergreen broadleaf forest

11

Permanent Wetlands

03

Deciduous needleleaf forest

12

Croplands

04

Deciduous broadleaf forest

13

Urban and built-up

05

Mixed forests

14

Cropland/natural vegetation mosaic

06

Closed shrublands

15

Snow and ice

07

Open shrublands

16

Barren or sparsely vegetated

08

Woody savannas

17

Water bodies

09

Savannas

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Error Sources

Errors in the input data represent the primary source of error in this data set. See Data Corrections Applied in the User Guide for EASE-Grid and EASE-Grid 2.0 Land Cover Classifications Derived from Boston University MODIS/Terra Land Cover Data.

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Version History

The following tables show the version history for these data sets.

Table 6. Version History for EASE-Grid LOCI Masks

Table 7. Version History for EASE-Grid 2.0 LOCI Masks

Version

Date

Description

Version

Date

Description

V1.0

2004

The EASE-Grid LOCI masks were created as an ancillary data set, not part of the official NASA DAAC data catalog. Instead, some of the data were distributed as ancillary data via a web page and others via personal communication with the authors.

V1.0

2011

The EASE-Grid 2.0 LOCI masks were created as an ancillary data set, not part of the official NASA DAAC data catalog. Instead, the data were distributed via personal communication with the authors.

V1.1

2014

These data were accessioned into the NASA DAAC catalog and given a data set ID number. During this process, NSIDC changed the title, filenames, and organization of the data to improve usability. For example, the file name for the Northern Hemisphere 25 km LOCI mask was changed as follows:

Nl_loci_land50_coast0km.721x721.bin (old name)

Nl.LOCImask_land50_coast0km.721x721bin (new name)

V1.1

2014

These data were accessioned into the NSIDC system and given a data set ID number. During this process, NSIDC changed the title, filenames, and organization of the data to improve usability. For example, the old file name for the Northern Hemisphere 25 km mask was changed as follows: